FLEX is based on a different mindset than current frameworks. Most frameworks have a set structure within which you can add practices. People want to know what to do and frameworks provide this. But the pervading idea is that at the beginning people must just adopt the framework. This has two bad side-effects which I believe are the causes of much of the bad Agile we see out there. The first is that the framework rarely fits the organization perfectly. A slight variance is not bad, but the disparity between the framework’s starting point and what would fit them better creates a dissonance. This not only hurts effectiveness but often creates resistance because the dissonance will create extra work for people who are already overloaded. The second side effect is that you are subtly teaching people to follow.
The way to solve these two challenges is not difficult but takes experience. The first is that some method of tailoring the framework or starting point must be used. The second is that you always emphasize the why of any practice and provide a method for improving or substituting it when challenges occur. Both of these can draw from the deep experience 20 years of Agile now provides – giving us patterns of challenge and success.